Background: Extended-spectrum beta-lactamases (ESBL) producing isolates of Klebsiella pneumoniae which have been increased in the hospitals were resulting in limitation of therapeutic options. The aims of this study were to evaluate the antibiotic susceptibility pattern and presence of ESBL genes in clinical isolates of Klebsiella pneumoniae from patients admitted to the intensive care units (ICUs).Materials and Methods: In this descriptive cross-sectional study, a total of 65 Klebsiella pneumoniae strains were isolated from ICUs of educational hospitals in Tehran. Identification was performed using biochemical tests and the antimicrobial susceptibility was performed as recommended by the Clinical and Laboratory Standards Institute (CLSI). Molecular analysis of the ESBL genes was performed by Multiplex PCR (M-PCR).Results: Most of the isolates were resistant to Cotrimoxazole (72.3%), Gentamicin (67.7%) and Ampicillin (69.2%) and the highest susceptibility was seen for Ciprofloxacin (50.8%) Tetracycline (49.2%), Imipenem (46.3%) and Ceftriaxone (43.1%). Among the ESBL-producing genes, blaCTX-M (55.3 %) was the most prevalent, followed by blaTEM (41.5 %) and blaSHV (10.7 %). The results showed that 1.5 % of the isolates had concurrently blaTEM/ blaSHV and blaSHV/ blaCTX-M genes and 21.6% of isolates the blaTEM/ blaCTX-M genes.Conclusion: These findings reveal the high prevalence of multi drug resistant and ESBL-producing Klebsiella pneumoniae in patients hospitalized in ICUs and emphasize the need for appropriate infection control policies.